Fitted bed sheet and method of manufacture

ABSTRACT

A fitted bed sheet is adapted for use with a relatively thin mattress having cutaway corners. The fitted sheet is formed from a blank of sheet material to have corner pockets that easily fit over the mattress corners. In particular embodiments the sheet is formed from the blank by a series of folding operations and is then stitched at the corner pockets to complete the sheet. The resulting fitted sheet may be ironed in conventional flat-ironing machines and may be folded into a compact form by an automatic folding machine.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to fitted bed sheets and methods of forming suchsheets.

2. Description of the Prior Art

Conventional fitted sheets or "contour" sheets having elastic orshirring at the corners have been in widespread use for years to serveas the bottom sheet overlying standard mattresses. Because of thewell-known problem of flat sheets loosening when used as the bottomsheet on hospital beds, particularly when the bed is articulated,conventional three-dimensional type fitted sheets have been used to someextent in hospitals. However, for a number of reasons such conventionalfitted sheets are unsuitable for hospital and other institutional uses.Among these reasons is the high cost of such fitted sheets. Further, theelastic at the corners tends to break down in the laundering and ironingprocess. These conventional sheets are also difficult to handle intypical flat-ironer machines. To eliminate ironing, the fitted sheetshave been manufactured with blends of natural and synthetic fibers sothat they may be conditioned and dried in tumblers or they may beair-dried. However, this requires the use of particular types of fibersand increases the expense.

Furthermore, conventional fitted sheets cannot be handled by automaticfolding machines. Because of the sheets' three-dimensional (or"developed") shape, any folding process (hand or automatic) results inan uneven, space-consuming volume that does not lend itself to neatstacking. Yet another disadvantage of conventional fitted sheets is thatthe bed making operation requires considerable physical effort because arelatively heavy and inflexible mattress must be fitted at the cornersor ends to get the sheet in place.

Therefore, there is an acute need for a fitted sheet that will overcomethese disadvantages, especially for hospital and other institutionaluses.

SUMMARY OF THE INVENTION

In accordance with the present invention a fitted sheet is provided thatovercomes the disadvantages of the prior art practices, particularlywhen the sheet is designed for use in association with a relatively thinmattress having cutaway or chamfered corners. The sheet of the inventionis made without elastic or shirring at the corners, thereby reducingcost and rendering the sheet suitable for ironing on flat ironingmachines and folding by automatic folding machines. Further, the sheetsof the invention may greatly reduce labor costs associated with bedmaking and mattress handling.

In accordance with one aspect of the invention, there is provided afitted bed sheet for use in association with a particular type ofoctagonal mattress for use on hospital type beds. The fitted sheetcomprises an octagonal panel whose perimeter defines a pair of opposedsides, a pair of opposed ends and four corners, with each corner joininga side to an adjacent end. The sides of the sheet are approximatelythree times the length of the ends and approximately five times thelength of the corners. The fitted sheet further includes a continuouspanel joined to the octagonal panel along a juncture running the entireperimeter of the octagonal panel. The continuous panel overlies acontinuous perimetric portion of the octagonal panel and has a widththroughout its course of approximately one-fourth of the distance thatseparates the sides.

The fitted sheet may be formed by folding a blank of sheet material inwhich case the juncture may comprise fold lines.

In a particular embodiment each corner on the perimeter of the octagonalpanel has a substantially equal length, C, and forms angles on the orderof 135° with the adjacent sides and ends. In this embodiment, the fittedsheet may be conveniently formed so that the width of the portions ofthe continuous panel that run along the sides and ends is on the orderof C/√2.

In accordance with another aspect of the invention, there is provided afitted bed sheet for use in covering a mattress that is rectangularexcept for cutaway or chamfered corners thereof. The cutaway corners ofopposite ends of the mattress provide what may be termed a male "lead inchamfer" at each end. The fitted sheet comprises a substantiallyrectangular central panel having a main portion approximating the sizeand shape of a mattress to be covered and corner portions whichapproximate in size and shape the corners which have been cut away fromthe mattress to be covered. The cutaway corners of the sheet correspondwith the cutaway corners of the mattress and provide what may be termeda female "lead in chamfer." The boundary between the main portion andeach corner portion of the central panel defines a corner fold line. Thefitted sheet further includes opposing side and end panels formedintegrally with the central panel to define side and end fold lines. Theside and end panels are inwardly folded along the side and end foldlines to overlie a marginal perimetric portion of the central panel andthe central panel corner portions are inwardly folded along the cornerfold lines to overlie portions of the adjacent inwardly folded side andend panels and are secured thereto to form corner pockets for receivingcorners of a mattress to be covered.

For use in covering mattresses having corners which are angled at 135°to the adjacent mattress side and end edges, the fitted sheet of theinvention may be formed with side and end panels that are substantiallythe same width and with corner pockets that are angled at 135° to theadjacent side and end fold lines.

The central panel corner portions and adjacent side and end panels maybe secured together by stitching, preferably stitching which comprises atriangular pattern along the outside edges of the corner portions. Themale lead in chamfer on the ends of the mattress and the female lead inchamfer on the ends of the sheet easily mate with each other so that thesheet may be easily placed in position on the mattress to cover the top,sides, and bottom perimeter portions thereof.

In accordance with yet another aspect of the invention, there isprovided a method of forming a fitted bed sheet from a blank having thedescribed rectangular central panel, opposed side panels and opposed endpanels. The method includes the steps of folding the side and end panelsinwardly along their respective fold lines and onto the central panel,folding each central panel corner portion inwardly along its respectivecorner fold line to overlie portions of the adjacent inwardly foldedside and end panels, and securing each central panel corner portion tothe adjacent inwardly folded side and end panels.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription thereof taken in connection with the accompanying drawings,which forms a part of this application and in which dashed lines denotethe "fold lines" and dotted lines denote stitching.

FIG. 1 is an isometric view of a blank of sheet material prior to beingfolded and stitched to form a fitted bed sheet of the invention;

FIG. 2 is a view similar to FIG. 1 showing the blank after the sidepanels have been inwardly folded along their respective fold lines;

FIG. 3 is a view similar to FIG. 2 showing the blank after the endpanels have been inwardly folded along their respective fold lines;

FIG. 4 is a view similar to FIGS. 2 and 3 showing the complete fittedsheet;

FIG. 5 is an isometric view of a mattress of a type suited for beingused in association with the fitted sheet of the invention;

FIG. 6 is a bottom view of the mattress of FIG. 5 after having beencovered by the fitted sheet of the invention;

FIG. 7 is an enlarged, fragmentary view of a corner of the completesheet after having been turned insideout to better illustrate thestitching pattern;

FIG. 8 is an enlarged, fragmentary view of one corner of the sheet inplace over a mattress;

FIG. 9 is an enlarged view of one corner of the blank of sheet materialshown in FIG. 1;

FIGS. 10 and 11 are enlarged views of corners of two other blanks fromwhich fitted sheets within the scope of the invention may be made;

FIG. 12 is a pictorial view of a fitted sheet of the invention in thefolded state; and

FIG. 13 is a pictorial view of a conventional contour sheet havingelastic and shirring, in the folded state.

DETAILED DESCRIPTION OF THE INVENTION

While the present invention will be described hereinafter withparticular reference to the accompanying drawings, it is to beunderstood at the outset of the description which follows that it iscontemplated that the present invention may be varied in specific detailwhile still achieving the desirable characteristics and features of thepresent invention. Accordingly, the description is to be understood as abroad enabling teaching directed to persons skilled in the applicablearts, and is not to be understood as restrictive.

Referring to the drawings, and particularly to FIGS. 1-4, there is shownin sequence the stages of forming a particular embodiment of the fittedbed sheet 10 of the invention from a blank 20 of sheet material. Sheet10 is preferably formed from textile material of a type suitable for usein bed sheets, but may be formed from other suitable material, such asdisposable non-woven material. While not shown in the drawings, the endsof the blank may be hemmed by straight stitching to avoid unraveling andthe side edges may be formed selvages, or hemmed.

The illustrated sheet is adapted for use in covering a mattress such asmattress 80 of FIG. 5. Mattress 80 is substantially rectangular exceptfor the "cutaway" or "chamfered" corners 82, which actually give themattress an octagonal shape. The advantages of this mattressconfiguration and the manner in which it cooperates with the fittedsheets of the invention will be discussed in detail below.

Blank 20 includes a rectangular central panel 22, a pair of opposed sidepanels 24, 26 and a pair of opposed end panels 30, 32. The side and endpanels are formed integrally with the central panel 22 to define sidefold lines 34, 35 and end fold lines 36, 37.

The rectangular central panel 22 has a main portion approximating thesize and shape of a mattress to be covered (e.g., mattress 80) and fourcorner portions which approximate in size and shape of the corners whichhave been "cut away" from the mattress to be covered. Thus, in theillustrated embodiment the main portion is octagonal and the cornerportions are triangular. The boundary between the main portion and eachcorner portion defines a corner fold line 60.

The first stage of forming the fitted bed sheet 10 is illustrated inFIG. 2 wherein side panels 24, 26 have been inwardly folded along theirrespective fold lines 34, 35 to overlie marginal perimetric portions ofthe central panel 22. Next, end panels 30, 32 are inwardly folded alongtheir respective fold line 36, 37 to form the intermediate stage ofmanufacture shown in FIG. 3.

In the next stage of manufacture, the central panel corner portions areinwardly folded along their respective corner fold lines 60 to overlieportions of the adjacent inwardly folded side end panels. As shown inFIG. 3, the central panel corner portion is preferably folded such thatthe outer point "O" overlies the inner point "I." The completed sheet 10is formed by securing the central panel corner portions to theunderlying side and end panels.

Referring to FIGS. 7 and 8, there is shown the preferred manner ofsecuring the corner portions. A triangular pattern of straight stitches62, 64, 66 secure the material at the edges of the triangle that isformed when the corner portions are folded over. In addition, a stitch68 secures the triangular gusset 50 (discussed below) that is sandwichedin the layers of material. The stitching pattern lends itself to rapid,automatic sewing.

It will be appreciated that the complete fitted sheet 10 has cornersthat are angled at angles A and B (FIG. 4) of 135° to the adjacent sideand end fold lines. The sheet is, therefore, adapted to fit over amattress having similar cutaway corners. The 135° angles are bestachieved by providing side and end panels of equal width. By varying thewidths of the side and end panels and/or varying the positioning of thefold lines, the fitted sheet of the invention may be provided withangles other than 135° to both the side and end. For example, the cornermay form an angle A of 130° with the side fold line and an angle B of140° with the end fold line to accommodate a mattress with corners socut away.

Referring back to FIG. 4, it can be seen that the complete fitted bedsheet product of the invention may be defined as follows. The fittedsheet comprises an octagonal panel whose perimeter defines a pair ofopposed sides, a pair of opposed ends and four corners, with each cornerjoining a side to an adjacent end. In actual practice of the invention,the sides should be approximately three times the length of the ends andapproximately five times the length of the corners. The complete fittedsheet product further includes a continuous panel joined to theoctagonal panel along a juncture running the entire perimeter of theoctagonal panel. The continuous panel overlies a continuous perimetricportion of the octagonal panel and should have a width throughout itscourse of approximately one-fourth of the distance separating theopposed sides.

In the particular embodiment illustrated in FIG. 4, each corner on theperimeter of the octagonal panel has a substantially equal length C, andforms angles on the order of 135° with the adjacent sides and ends.Further, it can be seen that the width of the portions of the continuouspanel that run along the sides and ends is equal to C/√2. Thisrelationship exists because the corners form the hypotenuse of right,equilateral triangles, the sides of which are equal in length to thewidth of the mentioned panel portions.

As stated above, fitted sheet 10 is particularly well adapted for usewith a mattress such as mattress 80 illustrated in FIGS. 5 and 6.Preferably, mattress 80 is a relatively thin mattress on the order of31/2 inches in thickness and, because of its ability to easilyarticulate and other characteristics, is well suited for use in ahospital environment. Mattress 80 may take the form of the "top pad" ofthe mattress assembly described in copending application Ser. No.129,620, filed Mar. 12, 1980, now U.S. Pat. No. 4,316,298, issued Feb.23, 1982, except that the corners of mattress 80 are preferably cut awayas at 82. The teachings of said copending Ser. No. 129,620 now U.S. Pat.No. 4,316,298 are incorporated herein by reference.

Because mattress 80 is relatively thin, as opposed to usual mattresseshaving a thickness on the order of 5 to 6 inches, the "undeveloped"two-dimensional configuration of the corner pockets of sheet 10 is welladapted to conform to the mattress corners. With the mattress cornerscutaway as shown at 82, the undeveloped corners of sheet 10 slip easilyover the mattress corners. Since portions of the side panels 24, 26 andportions of the end panels 30, 32 underlie a peripheral portion of themattress 80 (FIG. 6), it is virtually impossible to dislodge the sheetfrom the mattress, even when the mattress is used on a hospital bed andarticulated in one or more locations, so that the sheet stays neatly andsecurely in place on the mattress.

As shown in FIG. 8, the stitch 66 at each corner pocket of sheet 10 isadapted to reside along the cutaway corner of the mattress. While stitch66 may reside along the upper edge of the mattress corner, in practiceit best resides along the corner approximately halfway between the topand bottom surfaces of the mattress. This positioning of the cornerpockets of sheet 10 provides an excellent, tight fit that cannot beachieved on a thin mattress with a conventional fitted sheet.

The particular blank 20 used to form the illustrated fitted sheet 10 isshown in FIG. 1, with an enlarged view of one corner thereof being shownin FIGS. 7 and 8. Material has been removed from the outwardly lyingportion of each blank corner area (as defined by extensions of the sideand end fold lines and extensions of the outside edges of the side andend panels) leaving a gusset 50 as the only material in the blank cornerarea. The use of this particular blank configuration serves to providethe desired strength and integrity at the corner pockets of the fittedsheets without the unnecessary bulk that results from the use of a fullrectangular blank. Gusset 50 may be easily stitched in place and servesto reinforce the corner pocket where it is subject to wear.

OTHER BLANK CONFIGURATIONS

As noted above, a blank 20 as shown in FIG. 1, or a full rectangularblank, may be utilized to form fitted sheets in accordance with theinvention. What is desirable is that when the central panel cornerportions are inwardly folded, the corner portions should overlie somepart of the adjacent side and end panels so that the corner portions maybe secured thereto to form a corner pocket of the fitted sheet. Thisdesirable result may be achieved with various blank configurations. Twosuch configurations are illustrated in FIGS. 10 and 11 which show thecorners of blanks 120 and 220, with the reference numerals, as increasedby 100 and 200, respectively, referring to corresponding elements ofblank 20.

EXAMPLE

A sheet was formed for use with a mattress as shown in FIG. 5 whereinthe mattress length was 78 inches, the mattress width was 35 inches, themattress thickness was 31/2 inches, and the corners were cut away toform angles A and B of 135° with the adjacent sides and ends of themattress. The dimensions X and Y (FIG. 5), corresponding to the amountby which the ends and sides of the mattress were shortened by thecutaway mattress corners, were both 81/2 inches.

The fitted sheet designed to accommodate this mattress was formed from ablank having the configuration shown in FIG. 1. The overall dimensionsof the blank were 95 inches by 52 inches. The side and end panels wereboth 81/2 inches wide. The gussets 50 were right, equilateral triangleshaving equilateral sides measuring approximately 11/2 inches.

The fitted sheet was formed by folding and then stitching in thetriangular pattern discussed above. The fitted sheet had an octagonalpanel with the distance between the opposed ends being 78 inches and thedistance between the opposed sides being 35 inches. The width of theportions of the continuous overlying panel that run along the sides andends was on the order of 81/2 inches (the width of the side and endpanels). The corners of the octagonal panels were substantially equal inlength and formed angles of 135° with the adjacent sides and ends. Thus,the length C, of the corners was on the order of 81/2 inches×√2=12.02inches.

OTHER FEATURES AND ADVANTAGES

The initial cost of sheets manufactured in accordance with the inventioncan be competitive because the amount of material used is approximately68% of that used for a standard flat sheet. (A standard sheet is66"×104" or 6,864 square inches, whereas the blank sheet 10 of the aboveexample is 4,676 square inches.) Cutting is simple, and sewing isstraightforward and easily automated. The sheets of the invention do nothave (not do they require) elastic or shirring. Since they can be madeof the same fabric as flat sheets, they will withstand processing aswell as flat sheets and do not require air drying.

The two dimensional sheets of the invention can be processed throughtypical flat-ironing machines at rates the same or better than standardflat sheets. Since the overall area to be ironed is approximately 40% ofa regular flat sheet, the production rate can be considerably higher.Furthermore, the sheets may be readily handled by an automatic foldingmachine. The sheets fold neatly and stack compactly as shown by thecomparison of a folded sheet 10 of the invention (FIG. 11) and a foldedconventional fitted sheet 90 with elastic (FIG. 12).

The sheets of the invention are extraordinarily easy to put on and takeoff mattresses, especially thin mattresses formed with cutaway corners.Because the thin mattress is light and extremely flexible, it is notnecessary to expend great physical effort to make the bed, nor does theattendant have to get to the head of the bed to get a neat fit; the bedcan be made from the sides.

The sheets can find excellent application whereever thin mattresses ofthe type described in copending application Ser. No. 129,620 now U.S.Pat. No. 4,316,298 can be utilized, for example, in hospitals, domesticapplication, hotels, dormitories and other institutions. A particularapplication of the sheets is for use in the sofa bed market, which isconstrained to the use of thin mattresses because of the extremearticulation of the mattress support mechanism. The two dimensionalsheets of the invention will stay in place even during the bending andunbending modes of the mattress in this type of application. Use ofstandard contour sheets on these thin mattresses is very unsatisfactory.

Another significant application for the sheets is in the increasingmarket for electric beds for domestic use (reading, television, etc.).All of the problems associated with articulating hospital beds and sofabeds apply to such beds.

Hospitals and other institutions may realize significant advantages inusing the more manageable sheet 10 of the invention to gain user comfortwithout sacrificing economy, particularly when used in association withthin mattresses having a thickness on the order of 31/2 inches or less.The engagement of the two dimensional sheet with the top, sides andbottom perimeter portions of the thin mattress provides full stabilityof the sheet on the mattress at all times, even when the mattress isarticulated. The ease of mattress handling and bed making represents anidentifiable reduction in labor costs.

The sheets of the invention may also facilitate the introduction ofdisposable non-woven fiber bed sheets to the institutional market. Suchattempts have met with very limited success, largely due to thenoncompetitive cost per unit. However, it is significant to note thatsheet 10 uses only 68% of the material required for a standardnon-fitted sheet and it can be manufactured simply and can be folded andpackaged compactly. The smaller area and lower weight of sheet 10obviates some of the disadvantages associated with the bulk of ultimatewaste disposal and results in the use of less storage space in thecentral warehouse and on the linen cart.

While the invention has been described in connection with a preferredembodiment, it will be appreciated that modifications may be madewithout departing from the true spirit and scope of the invention.

What is claimed is:
 1. A fitted bed sheet for use in association with anoctagonal mattress, said fitted sheet comprising an octagonal panelwhose perimeter defines a pair of opposed sides, a pair of opposed endsand four corners each corner joining a side to an adjacent end each ofsaid opposed sides being at least twice as long as each of said opposedends, and a continuous panel integrally joined to said octagonal panelalong a juncture comprised of fold lines running the entire perimeter ofsaid octagonal panel.
 2. A fitted bed sheet as claimed in claim 1wherein each corner on the perimeter of the octagonal panel has asubstantially equal length C, and forms angles on the order of 135° withthe adjacent sides and ends.
 3. A fitted bed sheet as claimed in claim 2wherein the width of the portions of the continuous panel that run alongthe sides and ends is on the order of C/√2.
 4. A fitted bed sheet formedfrom sheet material and adapted for use in covering a mattress that issubstantially rectangular except for cutaway corners thereof, saidfitted sheet comprising a rectangular central panel having a mainportion approximating the size and shape of a mattress to be covered andcorner portions which approximate in size and shape the corners whichhave been cut away from the mattress to be covered, the boundary betweenthe main portion and each corner portion defining a corner fold line,opposing side and end panels formed integrally with said central panelto define side and end fold lines with said central panel, said side andend panels being inwardly folded along said side and end fold lines tooverlie a marginal perimetric portion of the central panel, and saidcentral panel corner portions being inwardly folded along said cornerfold lines to overlie portions of the adjacent inwardly folded side andend panels and being secured thereto to form corner pockets forreceiving the cutaway corners of a mattress to be covered.
 5. A fittedsheet as claimed in claim 4 wherein said central panel corner portionsare triangular and said corner fold lines are at 135° angles to theadjacent side and end fold lines.
 6. A fitted sheet as claimed in claim4 or 5 wherein the widths of said side and end panels are substantiallythe same and are on the order of 81/2 inches.
 7. A fitted sheet asclaimed in claim 4 wherein the central panel corner portions andadjacent side and end panels are secured together by stitching.
 8. Afitted sheet as claimed in claim 7 wherein the stitching comprises atriangular pattern along the outside edges of said corner portions.
 9. Afitted sheet as claimed in claim 4 wherein the sheet material from whichsaid fitted sheet is formed is a blank that is rectangular except thatin the blank corner areas, as defined by extensions of said side and endfold lines and extensions of the outside edges of the side and endpanels, an outwardly lying portion of each such blank corner area isdevoid of material.
 10. A fitted sheet as claimed in claim 9 whereineach blank corner area includes a gusset at the intersection of therespective side and end fold lines, with the remaining area of eachblank corner area being devoid of material.
 11. A fitted sheet asclaimed in claim 10 wherein the central panel corner portions andadjacent side and end panels are secured together by stitching in atriangular pattern along the outside edges of said corner portions andsaid gusset is secured therebetween by stitching.
 12. A method offorming a fitted bed sheet comprising the steps of:forming a blankincluding(i) a substantially rectangular central panel having a mainportion approximating the size and shape of a mattress to be covered andcorner portions that approximate in size and shape the corners whichhave been cut away from the mattress, the boundary between the centralpanel main portion and each corner portion defining a corner fold line;(ii) a pair of opposed side panels, each side panel being formedintegrally with said central panel to define a side fold line with saidcentral panel; (iii) a pair of opposed end panels, each end panel beingformed integrally with said central panel to define an end fold linewith said central panel; folding the side panels inwardly along therespective side fold lines and onto the central panel; folding the endpanels inwardly along the respective end fold lines and onto the centralpanel; folding each central panel corner portion inwardly along itsrespective corner fold line to overlie portions of the adjacent inwardlyfolded side and end panels; and securing each central panel cornerportion to the adjacent inwardly folded side and end panels.
 13. Amethod as claimed in claim 12 including the step of forming the blankwith gussets at the intersections of the side and end fold lines.